SCSI-3 Conundrum

Gene Milligan Gene_Milligan at
Mon Jun 2 10:09:49 PDT 1997

* From the SCSI Reflector (scsi at, posted by:
* Gene Milligan <Gene_Milligan at>
In the process of dealing with the ANSI pre-edits for SBC I have noticed that 
SPC is an acronym for two different items in SCSI-3.

The original meaning of SPC is found in SCSI-2 and SBC which is "The step pulse 
per cylinder (SPC) field is used to specify the number of additional step 
pulses required per cylinder." For those not as familiar with SCSI as the 
members of the committee it will be confusing to have two different meanings 
for SPC (especially with the small caps distinction lost in ASCII excerpts as 
it is in this Email).

The additional new meaning which is found in SCSI-3 including SBC is "SCSI-3 
Primary Commands".

It seems to me there are two obvious alternatives to this conundrum:

 a) Rename NCITS 301-199X (e.g. SCSI-3 Overhead Commands (SOC)) and change 
references to it accordingly.

 b) Change the acronym of step pules per cylinder to (SPPC).

Certainly the correct thing to do to not injure the original implementors is 
choice (a). However since the injury would be infinitesimal and not noticed, I 
suggest being cavalier and taking choice (b).

Although T10 has already approved whatever I do in Rev 8a, I would like to know 
if there is any objection to changing the acronym of  step pules per cylinder 
to (SPPC)?

Gene Milligan
Technical Editor of SBC
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